Transmitter for repeater systems



April 12, 1949. A. P. :tmws Eflfifififi TRANSMITTER FOR REPEATER SYSTEMS Filed Dec. 21., 1945 2 Sheets-Sheet 1.

INVENTOR: A'whur P. Davis Apzrifi i2, A, F. DAV 1S 9 3 TRANSMITTER FOR REPEATER SYSTEMS Filed Dec. 21., 1945 2 Sheets-Sheet 2 IN VEN TOR.

' APHu/P P. Davis Patented Apr. it 1949 Anna tionofNewYork N. 1., a corpora- Application December 21, 1945, Serial No. 036,458

I Claims. (Cl. 177-680) 1 This invention relates to a repeater system for the remote indication of angular values, and has particular reference to repeater compass transmission systems, although the invention is not limited to that particular use.

The directional element of a compass, whether of the magnetic or the gyroscopic type, is necessarily, very delicately balanced to respond to the minute directive forces which cause it to give directional indications. For this reason, a direct drive from such a compass element of remote repeaters is not practicable and therefore it has been the custom to providemaster compasses with electronic servo or follow-up systems for following the sensitive element, and then provide power to drive the transmitters which control the distant repeaters. However, in order to function without any appreciable reaction on the sensitive element, such servo-systems are inordinately elaborate, expensive and delicate, and therefore susceptible to damage and require much maintenance attention.

In accordance with the present invention, a simple, rugged and inexpensive servo-system, especially adaptable for compass-repeater work or other purpose, is provided, which eliminates the objections to present systems. In a preferred embodiment of the invention. a magnetic element-is supported to rotate freelyin a conducting liquid contained in a receptacle having a series of contacts arranged on its inner peripheral surface and immersed in the liquid. On the outside of the receptacle, these contacts are connected together by a network of reactances having proportions calculated to prevent error in output and, at selected symmetrical points on this net-' work, leads are taken ofl. for transmission of angle-identifying currents to remote points for driving repeaters or other electrical receiver motors. Electric current is fed to the sensitive element through the liquid and is accordingly so apportioned through the contacts to theoutput terminals as to "give them the proper well-known Fig. 3 is a combination perspective view of the essential mechanical parts and an electrical diagram of the invention, for use in explanation of its action;

Fig. 4 is a fragmentary electrical diagram of the arrangement for preventing output distortion; and,

.Fig. 5 illustrates a preferred form of the contact armatures of the directionable element, as seen along line l! of Fig. 1.

Referring to Fig. 1 of the drawings, numeral l0 designates the directive unit which is represented as a permanent magnet compass element rotatable about vertical pivots and floating within a body of conducting liquid or electrolyte ll contained in stationary receptacle I 2. Element It includes a frame, preferably formed of plastic material, such as a phenolic resin, having suitable buoyancy chambers and housing a pair of bar magnets II. Arranged at right angles to the magnets l3 are radial fins acting on the liquid H as damping fins.

The upper edge of one of the fins I4 is fitted with a thin strip conductor l5 ending in the armature or electrode I6, while the lower edge of the other fin II is fitted with a strip conductor II terminating in an electrode It, as shown especially in Fig. 3. Both of these conductors l5 and I1 terminate at the center of the assembly in metal rings l9 and 20 as shown in Fig. 3,. these rings being isolated from each other as far as possible space-phased volage relations for angle indication commonly used in self-synchronous receivers, which may be of any suitable type.

For a more complete understanding of the invention, reference may behad to the accompanying drawings, in which:

Figure 1 is a plan view of the interior of one form of the invention as applied to a magnetic compass with th cover removed along the line ll of Fig- 2:

Fig. 2 is an axial section through the same, as

seen along the line 22 of i;

in the liquid N, although each ring is spaced as closely as possible to a similar conducting ring on the stationary parts of the assembly. Thus, movable ring I9 is close to stationary ring II on the cover I! and movable ring 20 is close to stationary ring 22 on receptacle 12.

The rings, 2| and 22, are connected as shown by wires 23 to a transformer 24, which is energized from the alternating current service leads 2!, so that the armatures II and 18 are supplied with electric power, preferably single phase alternating current through transformer 24, rings 21 and 22, electrolyte ll, rings is and 2c, and respective conductors l5 and I1 to electrodes l6 and I8, which are preferably of extended area and shape shown in Figs. 1 and 5, the purpose ofwhich will be explained. The single phase alternating current thus fed to electrodes l6 and.

I8 precludes electrolytic deposits in the manner described in detail in copending patent application serial No. 597,178, filed June 2, 1945, by applicant, now abandoned.

Immersed in the contained liquid II and uniformly spaced around the inner wall of the sta- BJQOJOS tionary receptacle are the series of contacts II,

which are close to but not in contact with electrodes is and it when overlapped thereby, as shown especially in Figs. 1 and 3. Any required number of such contacts 23 may be employed, such as th thirty-six shown, spaced ten degrees apart. The contacts 28 are connected to one end of corresponding wires 21 passing through the wallof the receptacle l2 and Joined together as shown by thirty-six reactance units 23 arranged in the circular series 23. At chosen symmetrical points on this series 23, such as points 33, 3| and 32 spaced one hundred and twenty degrees apart. leads 33 are attached to transmit the resultant space-phased currents to remote repeater receivers, two of which are shown at 34 and 35 supplied with electrical power by connection to the service leads 2!.

Inasmuch as the service leads 2' also supply voltage for the two electrodes It and II which travel around in the electrolyte II, the desirable condition is obtained in the arrangement of this invention which is inherent in the best selfsynchronous transmissions, viz., that no current 'ilows from transmitter to receiver when their in dications are in agreement, since the spacephased voltages apportioned by the transmitter to leads 33 are exactly balanced by those generated in the repeaters 34 and 35, as is well understood in self-synchronous systems.

In this way, the current energy dissipated in the electrolyte ll of the transmitter in heat and electrolysis is reduced to that represented by the unavoidable stray or leakage current therein. and the current in the reactance network. Such leakage current is reduced to a minimum by making the leakage paths, especially those between points of relatively high potential dinerence, as long as possible by placing such parts remote from each other and by making. the current paths between them as tortuous'as practicable, as shown in Fig. 1.

Since leakage of electrical current also occurs between any one of the contacts 26 and every other one of them in an amount proportional to the diilerence in potential in each case and, since these currents obviously have a complicated relation to the angular position of the electrodes I3 and it, it has been found desirable to provide for a certain relation between the ohmic value of the various individual resistances 23 of the network group 23. Such a special arrangement is illustrated in Fig. 4, in which one of the six parts of the network resistances 29, being a threephase'system, is shown as comprising six resistors 23 of the thirty-six resistance system shown.

Each such six-resistor group is then split into two sections, the units of which are similar but arranged in reverse order, as shown in the drawing, so that the units 230, for instance, have an ohmic value of 19 ohms in one arrangement, the

next two resistances 28b, have the lesser ohmic value of 18 ohms, and the final two resistances 28c, have the value of 17 ohms. This group of six values is repeated, as has been stated, six times around the complete circle of the network 29 and the total assembly in use brings about true sine form output voltages in the leads 33 as functions of the angle of the directive element It with respect to the terminals 30, 3| and 32.

As above stated, in the preferred arrangement thirty-six contacts are used and if the electrodes l6 and I8 cooperating with these contacts are rectangular in shape and about the same proportions as the contacts 26 as shown in Fig. 3, for

example, then there appears a ripple in the output voltages which may cause the repeater pointers to vibrate. This ripple may be raised in frequency and decreased in amplitude by increasing the number of contacts 23, but this expedient leads to manuiacturing complications, and it is therefore preferred not to increase the number of contacts. This condition is corrected by specially shaping the two electrodes l3 and II as shown in Fig. 6, and making the electrodes of increased width in order to overlap several contacts 2! in the liquid II, as shown in Figs. 1 and 2. The pointed ends 33 of the electrodes II and II serve to vary the currents passing from the electrodes |3, |3 to the neighboring contacts 2| in a smooth and uninterrupted manner as the electrodes pass by the contacts 23. The shape shown in Fig. 5 has been found to produce substantially rippleiree outputs on the leads 33.

The operation of the self-synchronous compass repeater system oi this invention is readily understood from the foregoing description and may be summarized as follows: North-seeking movements of directional element I! about its vertical axis result, in relative movement between the same and receptacle l2, thus causing electrodesv II and i3 to overlap a diii'erent opposite group'of contacts 2' spaced therefrom by the thin intervening layer of electrolyte Inasmuch as the resistor series relations between the input at 2| and 22, the armatures l3 and II, the electrolyte intervening between the latter and the overlapped conductors 26, and the output across terminals 33, 3| and 32 varies, the

- eirective voltage values E1, E: and E: 01' the three segments of the network 23 between points 33, 3| and 32 change, and the resulting space-phased currents peculiar to that angular position 0! compass element II are fed to repeaters 34 and 35, whose pointers or cards accordingly indicate the compass direction in the usual way. As indicated, the voltages E1, E1 and It's have the proper space-phased voltage relations for angle indication commonly used in self-synchronous receivers, namely:

Ei=E sin a E2=E sin (mi-) E3=E sin (vi-240) where E is the maximum output voltage across any two'of the terminals 30, 3| and 32 and a is the angular position of the compass element It. As stated, by properly proportioning the ohmic resistances of the resistors 23, the preferred true sine form output voltages appear in the leads 33,

and ripple-free output is obtained by employing the specially-shaped electrodes shown in Fig. 5 without requiring an inordinately great number of contacts 28 to secure smooth operation. In these ways a simple and rugged repeater system is provided for compasses, whether of the. magnetic, gyroscopic or combined magnetic and gyroscopic types. Obviously inductances could also be used.

Although a preferred embodiment of the invention has been illustrated and described herein, it is to be understood that the invention is not limited thereby but is susceptible of changes in form and detail within the scope of the appended claims.

I claim:

1. In electromechanical transmitting apparatus, the combination of a container, an electrolyte in said container, spaced stationary e1ectrodes in said container in electrical contact with 2. In electromechanical transmitting apparatus,the combination of acontainer, an-electrolyte therein, stationary electrodes spaced circularly around the interior of said container and in electrical contact with said electrolyte, resistances interposed between adiaoent stationary electrodes and connected in series to form a resistance network, spaced terminals on said network, at least one movable electrode mounted for movement in spaced relation with said stationa ing so arranged that the-three voltages E1, E5 and E: developed between said three terminals are in accordance with the following laws:

where E is the maximum output voltage across any two of said terminals and a is the angular displacement of said pair of spaced apart electrodes from a reference position.

'5. In electromechanical transmitting appara-f tus, the combination of, a container having a conducting fluid therein, stationary electrodes spaced circularly around the. ,interiorof said container and in electrical contact with said conducting fluid, resistances interposed between adjacent staary electrodes about the center of the circle lyte therein, stationary electrodes spaced circu- I larly around the interior of said container and in electrical contact with said electrolyte, resistances interposed between adjacent stationary electrodes and connected in series to form a resistance network, spaced terminals on said network, a supporting member rotatively mounted about the center of the circle of said stationary electrodes, at least one movable electrode mounted on said member for movement in spaced relation with said stationary electrodes about the center of the circle thereof and cooperating electrically therewith through said electrolyte. a current-receiving terminal mounted on said member' remote from said movable electrode and in contact with said electrolyte, electrical connections between said terminal and movable electrode, and a stationary current-transmitting terminal mounted on said container in closely spacedrelation with said current-receiving terminal andin contact withsaid electrolytejo'r supplying current thereto through said electro-v lyte. 1

4. In electromechanical transmitting apparatus, the combination of a container having a conducting fluid therein, stationary electrodes spaced circularly around the interior of said container and in electrical contact with said conducting fluid, resistances interposed between ad- 'jacent stationary electrodes and connected in series to form a resistance network, three spaced apart terminals on said network, a pair of spaced apart, movable electrodes mounted for movement in spaced relation with said stationary electrodes about the center of the circle thereof and cooperating electrically therewith through said electrolyte, and a source of alternating current connected to said pair of movable electrodes, said resistors, terminals and movable electrodes betionaiy electrodes and connected in series to form a resistance network, three spaced apart terminals on said network, a pair of spaced apart, movable electrodes mounted for movement in spaced relation with said stationary electrodes about the center of the circlethereof and cooperating electrically therewith through said electrolyte, each of said movable electrodes having a width suillcient to overlap simultaneously two or more of. said stationary electrodes, and a source of alternating current connected to said pair of movable electrodes, said resistors, terminals and movable electrodes being so arranged that the three voltages E1, E2 and E3 developed between said three terminals are in accordance with the following laws:

Ei=E Bill a E2=E sin (ad-) E3=E Sill (a+240) where E is the maximum output voltage across any two of said terminals and a is the angular displacement of said pair of spaced apart electrodes from a reference position.

6. In electromechanical transmitting apparatus, the combination of a container having a conducting fluid therein, stationary electrodes spaced circularly around the interior of said container and in electrical contact with said conducting fluid, resistances interposed between adjacent stationary electrodes and connected in series to form a resistance network, three spaced apart terminals on said network, the values of said resistances being selected to vary progressively so as to prevent wave form distortion in the transmission, a pair of spaced apart, movable electrodes mounted for movement in spaced relation .with said stationary electrodes about the cenin surface area from a relatively small value at the outer edges to a larger value intermediate the outer edges, and a source of alternating current connected to said pair of movable electrodes. said resistors, terminals and movable electrodes being so arranged that the three voltages, E1, E2

and E: developed between said three terminals are in accordance with the following laws:

E1=E sin a Ez=E sin (a+120) Es=E sin (a+240) where E is the maximum output voltage across any two of said terminals and a is the angular displacement of said pair of spaced apart electrodes from a reference position.

7. In electromechanical transmitting apparatus. the combination oi a container having a conducting fluid therein, stationary electrodes spaced circularly around the interior of said container and in electrical contact with said conducting iiuid, resistances interposed between adjacent stationary electrodes and connected in series to form a resistance network, three spaced apart 10 terminals on said network, a pair oi spaced apart, movable electrodes mounted for movement in spaced relation with said stationary electrodes about the center of the circle thereoi and cooperating electrically therewith through said electrolyte, a pair of current receiving terminals remote from said respective movable electrodes and in contact with said electrolyte. electrical connections between said current receiving terminals and said respective movable electrodes, and a pair or stationary current transmitting terminals mounted on said container in closely spaced relation with the current receiving terminals, respectiveiy, and in contact with said electrolyte for supplying current to said current receiving terminals through said electrolyte. said resistors. terminals and movable electrodes being so arranged that the three voltages E1, E: and E: developed between said three terminals are in accordance with the followings laws:

Ei=l 9111 a Ea=l sin (at-H30) EJ=E sin (ml-240) where E is the output voltage across 8 4 any two or said terminals and a is the angular displacement 01' said pair oi spaced apart electrodes from a reference position.

aa'rmm. P. DAVIS.

REFERENCES CITED The following references are of record in the flle at this patent: 1

UNITED STATES PATENTS 

